In a performance evaluation of experimental design when an eyeglass lens is designed and developed or in a product comparison when a user considers the purchase of eyeglass lenses, there is a desire to employ a technique for evaluating objectively how well a view through lens design is visually perceived in practice. A human being views an object with two eyes, and therefore there is another desire to objectively evaluate visual perception when viewing an object with both eyes. There is still another desire to provide eyeglass lenses suitable for a user by calculating visual characteristics of the user or by calculating how to use the sight line of the user when the user purchases eyeglass lenses in the form of objective numerical values. The reason is that it is easy to choose eyeglasses suitable for a user if visual characteristics of the user and how to use the sight line of the user are beforehand known.
An visual acuity test that uses, for example, Landolt rings, E marks, or hiraganas, which is an existing method for ascertaining user's visual perception, is performed, and, as a result, it is possible to ascertain how well a user visually perceives such objects through a lens in accordance with user's subjectivity. Additionally, the use of, for example, an autorefractometer makes it possible to objectively measure the refractive power of user's eyes.